Transcript I._Introduction_to_Ecology

I. Introduction to Ecology
A. Organization of the BiosphereEarth’s life supporting layer of air, soil and
water.
1. Ecosystem- A physically distinct, self- supporting unit
of interacting organisms and their surrounding
environment.
a) Ecosystems vary greatly in composition and size
b) Ecosystems consist of two environmental factors
1)
Biotic Factors- All living things in an
ecosystem: producers, consumers and
decomposers
2)
Abiotic Factors- nonliving parts of an
ecosystem: light soil, water, wind temperature and
nutrients
2. Communities and Populations
a) Community- a group of
organisms that coexist in
an ecosystem and form a
system of production,
consumption and
decomposition
b) Population- many
individuals of a single
species that share a
common area and
resources
3. Habitats and Niches
a) Habitat- surroundings in which a particular
species can be found
b) Niche- way of life a species pursues within
its habitat
B. Flow of Matter in the
Ecosystem


Recycling- continuous
movement of chemicals
throughout the
ecosystem
Biochemical cyclepathway through which
a chemical substance is
recycled
3. The Water Cycle
4. Carbon Cycle
5. Nitrogen Cycle
3. Nitrogen Cycle
B)
78% of the air is nitrogen gas; however, it is
useless to living organisms.
Most living organisms use nitrogen on in the
form of nitrates (NO3-), nitrites (NO2-),
ammonia (NH3).
C)
Nitrogen Fixing- converting nitrogen gas
A)
to nitrates
D)
Ammonification- converting nitrogen
compounds
to ammonia and thin is is
converted into nitrates in a process called
nitrification
C. The Transfer of Energy
1. Trophic Levels
A) Producers- autotrophic plants
B) Consumers- heterotrophic animals
1) 1ST order consumers are herbivores- they eat only plants.
2) 2nd order consumers are carnivores- they eat other animals
3) Some consumers are omnivores- they eat both plants and
animals
C) Scavenger- animals that feed off dead organisms or
wastes. (Vultures, Jackals, rats and roaches)
D. Decomposer- breakdown dead organisms and
return the nutrients into the soil. (Bacteria, Protist &
Fungus.)
2. Food Chains pathway of energy through
an ecosystem.
Plants capture
approximately 1% of
the available light
energy from the sun for
biomass production by
way of photosynthesis.
Photosynthesis can be
described chemically as:
Light Energy + 6C02 +
6H20 = C6H1206 + 602
(1,000 Units of Energy)
Herbivores
consume
approximatel
y 10% of the
plant biomass
produced in a
typical food
chain.
(100 Units of
Energy)
Carnivores capture
and consume about
10% of the energy
stored by the
herbivores.
(10 Units of Energy)
3. Food Web network of interconnected food
chains
4.
Ecological Pyramids
a) Pyramid of Energy
The energy available for use by organisms at each trophic level
averages only about 10% of the preceding level
b) Pyramid of Biomass
Biomass- the weight of an organisms after the water
has been removed. Biomass decreases as you go up
each trophic level
2nd carnivore
1st carnivore
Herbivore
Producers
The pyramid of biomass is an energy pyramid based on the mass
of dry tissue of organisms at each trophic level. Decreased radiant
energy during the winter changes the number of producers and
therefore the energy made available to consumers. Ecosystems in
the winter have less biomass.
C) Pyramid of Numbers
The number of organisms decreases at each trophic
level
2nd carnivore
1st carnivore
Herbivore
Producers
The pyramid of numbers is an energy pyramid based on the number of organisms
at each trophic level, which can be drawn by counting the number of producers
(plants) in an area that support a number of herbivores, and in turn, higher-order
carnivores. There are many exceptions to this pyramid because physical size of
the members of a food chain can change the shape of it. For example, many
aphids can be found feeding on a single plant, so the bottom layer of the pyramid
would be inverted
II. Biotic Relationships
1. Competition and Predation
A) Competition- Struggle among
organisms for the limited natural
resources
1) Intraspecific competition competition by members of the same
species
2) Interspecific competitioncompetition with members of other
species
B) Predation- organisms consuming
other organisms. The predator eats
the prey
2. Symbiosis a permanent, close
relationship between two organisms of different
species that benefits at least one of them.
A) Mutualism- symbiotic relationship in
which both organisms benefit.
B) Commensalism- symbiotic
relationship in which one organism
benefits while the other is neither helped
nor harmed.
C) Parasitism- symbiotic relationship in
which one organisms benefits (parasite)
and one organism is harmed (host)
3. Biological Rhythms
Physiological
changes in response to naturally reoccurring phenomena
A) Circadian rhythm- Daily cycle sleep/wake
cycle


Diurnal- asleep at night, awake days
Nocturnal- awake nights, asleep days
B) Annual rhythm- biological rhythm that
occurs annually


Hibernation- reduction of activity by warm
blooded animals in the winter
Estivation- reduction of activity in summer